Meta-analysis: remission and response from control arms of randomized trials of biological therapies for active luminal Crohn's disease.

BACKGROUND: Remission and response are the main outcomes to evaluate the efficacy of new treatments for Crohn's disease (CD). AIM: To explain variation of remission and response rates in active luminal CD. METHODS: We studied control patients from trials of biological therapies through articles retrieved by MEDLINE search (from 1997 to 2007) and by bibliography review. Thousand nine hundred and thirteen control patients from 28 trials were identified; data were extracted by three independent observers and pooled by DerSimonian and Laird random effect model; factors influencing remission and clinical response were explored by metaregression for aggregated data. RESULTS: The pooled control rates of remission and response were 17% and 33%, respectively, both with significant heterogeneity among studies (P < 0.0001). At metaregression, the time of primary outcome evaluation was associated with remission, whereas the trial's criteria for defining response and publication year were predictors of response. CDAI score, CRP levels or other clinical variables related with disease activity or concomitant medications were not significant factors. CONCLUSIONS: Populations used as 'add-on' treatment comparator in trials of biological therapies for active luminal CD are poorly characterized and outcomes are heterogeneous. Planning of future trials will require better description of patients and concomitant therapies, blinding of outcome assessors and homogeneous criteria of outcome definition.